17th September 2009

Amerisur Resources Plc ('the Company')

Platanillo - Assignment of Interest

Amerisur Resources Plc, the oil and gas explorer and developer focused on South America is pleased to announce that its Colombian subsidiary, Amerisur Exploracion Colombia, has agreed to acquire the interest of Ecopetrol SA in the Platanillo contract.

The assignment of interest has been approved by the Agencia Nacional de Hidrocarburos (ANH). 

The Platanillo Field is located in the Putumayo basin, in the south of Colombia. The Company now holds a 100% working interest in the contract.

Dr. John Wardle, Amerisur´s Chief Executive Officer commented: 

'I am very pleased we have acquired the full working interest in this contract. Holding 100% of this block will bring immediate economic value and also gives the Company access to expanded options for the future appraisal of the field. We have now submitted the required paperwork for the award of the Exploitation Environmental License to the authorities and expect to begin commercial production before the end of this year. I look forward to informing shareholders on progress.'

Giles Clarke, Chairman commented: 

'We are very happy to have acquired the remainder of the working interest in this block, which is an important contract for us. We look forward to what will be an important cash flow for Amerisur, which will contribute to the further development of the field and our other operations in South America. '

- Ends -

The Company is operator of the block and currently holds a 100 per cent. working interest through its subsidiary, Amerisur Exploracion Colombia Limitada under the Platanillo Exploration and Production contract with the ANH. Ecopetrol S.A. previously held a 40% interest.

Competent person: Technical information in this announcement has been reviewed by John Wardle Ph.D., the Company's Chief Executive. John Wardle has 24 years experience in the industry, having worked for BP, Britoil, Emerald Energy and Pebercan, and is a trained drilling engineer. 

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